Bipolar magnetic control record



March 2, 1948. L ROTH 2,436,329

BIPOLAR MAGNETIC CONTROL RECORD Filed Jan. 51, 1945 V/ FIG! r7 5' I 2? k 20 27 l Dc 73% 24 SOURCE 34 35 F i-'32 m 32 40 36 m 7 [A 36' Q I S r \N '5 e .37 39 I L'Z'G.5.

+ H i O 1 1 2 3 4 5 6 7 8 9 O A E! 0 3 c O O O 0 O O O o o o C O 4 b Q i 7 ENVENTOR 5 ROBERT Ron-r 9 BY m I ATTORNEY P816115! Mar. 1

umrgp smras PATENT OFFICE Both, Hawthorne, N. Y., assignor to f International Business Machines Corporation, New York, N. Y., a corporation of New York Application January 31, 1945, Serial No. 575,511

'1 Claims. (01. ass-451.12)

This invention: relates to control records for card formed of magnetic spot record embodying record controlled machines and particularly to the invention.

s on the record,

records 'of the magnetic spottype. v Fig. 1 shows a soft iron backing plate ill, at One object of the invention is to provide a one side of which is positioned a record sheet ll record or this type having stronger magnetic 5 composed of, partially composed of, or coated spots, that is, spots-which will produce a stronger with, paramagnetic material. Preferably. the signal in a magnetic spot sensing device. record sheet is a special paper into which a mag- Another object is to provide a control 'record netizable material in finely divided state is inhaving'magnetic spots capable of producing discorporated when the paper is made. The mag-' -tinctly diflerent responses in a-s ensing device, netizable material should have a high coercive depending upon novel diiierentiating characterisforce. An alloy of aluminum, cobalt, nickel and tics'of thespot, Q j a g iron having the composition 12% A1, 20-28% Ni, Another object is to increase the capacity of a 5% Co, balance Fe, known commercially as record area, a I I Alnico, makes a particularly good magnetic spot Another object istoincrease the secrecy of a 15 record. Before being treated to produce magrecord." a i H 3 1 netic spots, the sheet is rendered uniformly non- Another object-is to provide a control record magnetized by any suitable means. whereonpositive .and negative amounts are dis- 1 0n the opposite side of thesheet i I from the tinguished by the nature 01 the individual spots backing plate I0 is a two-pole electromagnet I! which represent the; amounts by theirpositions having windings I: on its core it such that, when a r 7 I V a, current is passedthrough them, the .poles l5 and H Another object is toprovide a control record I6 will be oppositely magnetized. The windings whereon data are represented-by significantly lo- H of the magnet are connected to two blades i1, catedmagnetlc spots-havingfurtherdistinguishl8 of-a reversing switchv ilhaving cross-coning characteristics indicating, the class vnihthe nected contacts 20, 2|, and 22, 23. 'The contacts data.-

;v 22 and are connected to one side, of a Another object is to provide a control; record source of direct, current (not shown). andalso havin magn ti spots,repre senting. data in ac to one'piate of acondenser 24. @Thecontacts 2| e wherein the variables inand 2! are connected to a normally open terminal .;the;;positions oi; the spots, 25 Qf-a switch Itthe movable blade 2101 which tiati'n characteristics. oifiithe -inisconnected to:the,opposite side 01' the condenser I h 24 and normally rests againstacontact L8v conp nc iple of the invennected to the other side. of the sourceoi direct lects are-realiaedby current By ;throwing the switch blade v21 L lair magnetic spots, against thetcontact-H, when the reversing switch of he, -record sheet, is in the. position shown in Fig;'..-1,= the chargelon A the condenser 24 iiowsthrough the tcoils ofxthe Qn ili b pqmtg d ;,elect rom agnet in thedirejction tozrender the right Dunn, H mm iandficlajmssand ha mi pole [Ba-north poleandthetleft handipoie illustratedi thetaccemnanyineidrawmgs;iwmch 4 atsouth pole; This produces abinolar ma way oriexain ie; the princi-plepf ithe netic snotonthe r c rd a ing a s ut Do ea 1 Y its right 5,8I1d5-B-I1d38 north poleiatzits left end.

'l'he purpose of 1th? ba,cking; plate' 'l 0 is to con-- cent he u; and, thus produce avsharply'de v iter making agspot. .in:; the manneradescribed, e sheet U canlbe movedzzby-ianysuitablrmeans. 1U L lng'xi asdi e ent. iarjea; over:;the;\po1es-: of ,t ;.recordin magnets; :Also;theiswitch blade il is 15 m dic-contact .21.: to rechargefthe condenser itjthe bladesgzblade-rotatable;traversing 19 are throwntoztheoppositez'contactwll, and the blade .21- ismoved againstthemontact the dis harginga'current otthefondenser wili Q 5 psss through the coils of the electromagnet ln the the core 30 of an electromagnetic sensing device 3|, hereinafter called a sensing magnet, in the direction indicated by the arrow 32. The sensing magnet 3| has a coil 33 which can be connected to a storage device (not shown), or any means which is to be responsive to the magnetic spots. The record is shown with two highly magnified bipolar magnetic spots 3! and 35, the north poles 36, 36' of which point in opposite directions. It will be noticed that each magnetic spot is like a small bar magnet, the axis of which lies in the plane of the record sheet and parallel to a common reference line, which, in this case, is the direction of feed of the record sheet.

I have observed that, when spots of the kind shown in Fig. 2 are sensed by a sensing magnet, voltages are induced in the coil of the sensing magnet as shown in Fig. 3. Each spot induces a vo tage folowing a curve whichbegins with a small loop 31. 31' in one direction, then makes a sharp peak 38, 38' of much greater magnitude in the opposite direction, and finally passes through a small loop 39, 39' in the first direction. The two spots induce opposite voltages, due to the difierent orientation of their north poles. Thus, if the peak 38 of the voltage induced by the first soot is regarded as positive, the peak 38' induced by the second spot is negative. The reason for the peculiar voltage curves is as follows: The voltage induced in the coil 33 of the sensing magnet is directly proportional to the rate of change of flux in the core 30. As the record moves over the sensing magnet, the south pole 40 01 the first spot sets up a flux in the core 30, which increases in density until the center of the-core reaches the center of flux density ll emanating from the south pole of the spot. At this time the fiux density in the core 30 reaches a constant, maximum value, hence there is no change of fiux to induce a voltage in the coil of the sensing magnet. Up to the time when the center of the core reaches the spot II, the voltage inthe coil 33 traces the curve 31, reaching a maximum in the negative direction and returning to zero, being at all times directly proportional to the rate of change of flux density in the core. When the center or the core passes the spot 4 I, the iiux in the core decays, and a positive voltage is induced in the coil of the sensing magnet, indicated by the peaked curve 38. As the core of the sensing coil begins to'enter the fiux emanating from the north pole, flux of opposite direction is set up in the core, which hastens the rate of decay of the total flux in the core.

When the center of the core reaches a point midway between the south and north poles of the spot, the -flux in the core is changing at a maximum rate, hence the voltage induced in the coil of the sensing magnet is at its positive peak. From that point on, the flux becomes more and more predominantly controlled by the north pole of the spot and the voltage induced in the coil continues to be positive, but the rate of change 01 the flux decreases, until the center of the core reaches the spot 43, indicating the point of greatest density of the flux emanating from the north pole of the spot. At this time the rate of change oi the flux in the core of the sensing magwhich constitutes one of net becomes zero, the density oi the flux in the core having reached a maximum. The voltage induced in the coil is therefore zero. As the spot continues across the core, the flux in the core decays, reaching a maximum rate of decay when the center of the core passes some point between the point 43 and the boundary of the magnetic spot. The voltage induced in the coil 33 during this time traces the curve 39.

When the second spot crosses a core oi. the sensing magnet, the voltage traces a curve exactly the reverse of the one just described.

I believe theheight of the peak voltage, as compared tothe relatively small beginning. and ending curves, is due to several influences. First is the simultaneous influence oi the diminishing flux set up by the south pole and the increasing flux set up by the north pole, the latter increasing the rate of decay of the flux set up by the south pole. Also, the centers of density of the flux emanating from the south and north poles are shifted toward each other by their mutual infiuence, thus causing the rate of change of flux density in the core to be greater as the core moves between the points 4| and 43 of maximum fiux density in the two poles of the spot, than when the core is moved through the more dispersed fiux outside of thetwo centers of density. Whatever the reason, the voltage induced by a bipolar spot is considerably greater than that induced by a monopolar spot. In addition to this, the voltage induced by the bipolar spot is asymmetric, which affords the possibility of giving two distinct meanings to a spot, according to its orientation. The latter feature is of considerable importance in control records, because it means that a given amount of information can be represented on a smaller area. Thus, in a telegraphic tape it is possible to represent all the digits and the entire alphabet, as well as additional charaoters, 'by means of a 4-position bipolar magnetic spot code, wherein the orientation of the north pole of the spot is one of the variables. A small sample oi! a, telegraphic tape of this type is shown in Fig. 4. In this figure the spots are represented by arrows and their orientation is indicated by the direction in which the arrows point. A telegraphic tape of this kinds also has a higher degree of secrecy than one with monopolar spots, because the bipolar characteristic, the variables of the code. would not be readily detected.

Another advantage of the bipolar magnetic spot record is illustrated by the statistical card partially shown in Fig. 5. In this case the spots are again represented by small arrows. Those in field 50 represent the positive value 364, the positive nature of this value being represented by the orientation oi. the bipolar magnetic spots. In field 5| the spots have the reverse orientation, indicating that the number 2'7, which they represent, is a negative number. Field 52 contains spots representing the difference of the numbers in fields 50 and SI, namely 337. Since this is a positive value, the magnetic spots have the same orientation as those in field 50.

Positive and negative values are mentioned as illustrative of difierent classes of data which can be identified by oppositely orientated bipolar magnetic spots. The different orientations can be used to represent any other classification.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art, without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the followings claims.

What is claimed is:

1. In a control record for a record controlled machine having a monopolar reading device, the record being read by relative motion of the record and the reading device, a sheet of generally nonmagnetized material having significantly located discrete bipolar magnetic spots, the axes of the spots being in the plane of the sheet and parallel to the direction or relative motion of the record and the reading device.

2. In a control record for record controlled machines having monopolar means to read the control record in motion, a sheet of generally non-magnetized material having significantly located discrete bipolar magnetic spots, the axes of the spots being in the plane of the sheet and parallel to the direction of feed of the sheet.

3. In a control record for record controlled machines maving monopolar means to read the control record in motion, a sheet of generally non-magnetized material having significantly located discrete bipolar magnetic spots, the axes of the spots being in the plane of the sheet and parallel to the direction of feed of the sheet, and with either the north or south pole leading, depending upon the data signified.

4. In a control record for a record controlled machine having a monopolar reading device, the record being read by relative motion of the record and the reading device, a sheet composed at least partly of generally unmagnetized paramagnetic material having significantly located discrete bipolar magnetic spots disposed with their axes in the plane of the sheet and their north poles directed in either of two opposite directions parallel to the direction of the relative motion of the record and the reading device.

5. A record tape for reading by a monopolar tape reader, said record tape having discrete bipolar magnetic spots arranged thereon with their axes in the plane or the tape and parallel to its direction of feed, the spots being disposed in different code positions of the tape and with their north poles either leading or trailing, in accordance with a combinational code wherein the direction of the north pole of the spot is one of the variables.

6. In a control record for record controlled statistical machines having monopolar record reading means, the record being read by relative motion of the record and the reading means, a sheet composed at least partly of generally unmagnetized paramagnetic material having discrete bipolar magnetic spots located thereon in accordance with a statistical code, the axes of the magnetic spots being in the plane of the sheet with the north poles of the spots pointing in either of two opposite directions parallel to the direction of relative motion of the record and the reading means, depending upon the class of data represented by the spot.

7. In a control record for record controlled statistical machines having monopolar record reading means, the record being read by relative motion of the record and the reading means, a sheet composed at least partly of generally unmagnetized paramagnetic material having discrete bipolar magnetic spots disposed with their axes in the plane of the sheet and located in selected index point positions of different columns of the sheet parallel to the direction of relative motion of the record and the reading means, the columns being grouped in different fields and the spots in a certain field being oriented with their north poles pointed parallel to the columns in one direction, while the spots in another field are oriented with their north poles pointing in the opposite direction.

ROBERT I. ROTH.

REFERENCES CITED The following references are or record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,827,051 Thomas Oct. 13, 1931 1,949,409 Cohen Mar. 6, 1934 2,144,844 Hickman Jan. 24, 1939 2,361,752 Eilenberger Oct. 31, 1944 2,254,933 Bryce Sept. 2. 1941 

